Protecting means for electric circuits



June 17, 1924.

E. H. JACOBS PROTECTING MEANS FOR ELECTRIC CIRCUITS Filed Nov. 10 1919 Enneai H M056 Mm- M Patented June 17, 1924.,

UNITED STATES PATENT OFFICE.

ERNEST H. JACOBS, OF CHICAGO. ILLINOIS. ASSIGNOR TO ELECTRICAL ENGINEERS EQUIPMENT COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PROTECTING MEANS FOR ELECTRIC CIRCUITS.

Application filed November 10, 1919.

To all whom it may concern:

Be it known that I, ERNEST H. JACOBS, a citizen of the United States, residing in Chicago. in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Protecting Means for Electric Circuits, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to protecting means for electric circuits and more particularly to the provision of an improved resistance unit for lightning arresters and the like.

Electrical apparatus installed on light, railway power and high potential transmission circuits is subject to abnormally high potential stresses through various causes, such as lightning. switching, cable troubles and the like. Lightning is in all probability the worst of these conditions to be taken care of. These high potentials subject the apparatus momentarily to enormous stresses and it is, therefore. common to have some break down path in which the dynamic arc will be immediately rupture-d. I have observed that of the difficulties encountered in this connection, that of rupturing the dynamic are when it has once been started by a high potential discharge is in all probabil ity the most eminent. A resistance unit for use in this connection must be capable of relieving surges and the like, and at the same time of a resistance suflicient to limit the flow of dynamic current which tends to follow the surge upon relieving the same. Furthermore, if the resistance when placed between lines, is too low in case of discharge from phase to phase the circuit breakers or other automatic devices in the line will open, causing a temporary shut-down which is inadvisable as well as annoying.

It is the aim of'my invention to provide a novel, simple, inexpensive and compact resistance unit of sound mechanical construc tion, high resistance value and large capacity.

Various other advantages of my invention and novel structural details will appear from the following detailed description and from the accompanying drawings in which:

Figure 1 is a side elevational view of the Serial No. 336,954.

resistance unit, showing one manner of mounting the same;

Figure 2 is an enlarged elevational view of the resistance unit, and

Figure 3 is an enlarged detail sectional view partly in elevation of the same.

In order to impart a clear understanding of a. particular embodiment of my invention, I have illustrated in Figure 1 one instance of its employment.

The particular arrester shown comprises a pair of horn electrodes 1 and 2 and a pair of sphere electrodes 3 and 1, supported in suitable relation to each other upon the mounting pipes 5. The electrodes 1 and 3 are connected to the line by means of a suitable terminal 6 and the electrodes 2 and at are connected through the resistance unit 7 with which this invention is particularly concerned to ground. A line insulator 8 of sufficient insulating capacity to safeguard the voltage of the particular line forms an insulating support for the electrodes 1 and The insulator 8 is mounted through suit-- able clamping plates 9 upon the supportingpipes The top of the insulator 8 supports a clamp member 10, in which the electrodes 1 and 3 are mounted, preferably adjustably. The terminal 6 is in this particular instance braced by a line insulator 11 which insulator 11 is mounted through suitable clamping plates 12 upon the supporting pipes 5.

If it is desired to arrange the resistance unit 7 between two or more lines, the various lines are provided with a horn electrode 1 1 and a sphere electrode arranged in suit.

able relation about the electrodes 2 and 4 respectively. as shown. In this case the mounting pipes provide a common supportfor the line insulators 8 and 11, associated with the electrodes 1 and 3, and the insulators 16 and 17 associated with the electrodes 14 and 15.

The resistance unit 7, which resistance unit is mounted through suitable clamping plates 31 upon the supporting pipes 5, comprises a tubular casing 18, preferably cylindrical in form and made of suitable insulating material. The upper and lower ends of the tube 18 are provided with metallic caps 19 which caps 19 are threaded or otherwise suitably mounted upon the tube and close the upper and lower ends respectively thereof. The lower metallic cap 19 is provided with a terminal lug 20, through which lug the unit is connected to ground. The upper metallic cap 19 may be either connected to the electrodes 2 and i, as shown in Figure 1, or provided with a terminal lug 21 as shown in Figure The form shown in Figure 2 is adapted to be placed in series with the spark gap of the arrester by connecting it obliquely between either of the clamp members 10 and the mounting pipes 5, the electrodes 2 and 4: being omitted in such instance.

The resistance, which resistance is enclosed in the insulating tube 18 is built up of a number of vcoaxially arranged resistance rods 22 made of a compound of high resistance value and large capacity. The adjacent ends of the rods 22 are connected through suitable coupling sleeves 23. The opposite ends of the continuous resistance I rod thus provided, are mounted in metallic cap members 24.

Socket members 25, the sides of which socket members embrace the metallic cap members 24, as shown in Figure 3, are provided with axially projecting studs 26, which studs 26 bear in the upper and lower cap members 19 as shown. Coiled springs 27, arranged in the socket members between the bases thereof and the cap members 24, allow for different co-eflicients of expansion between the resistance rods 22 and the insulating tube 18. If the resistance rods 22 were arranged rigidly in place, different rates of expansion between the rods and the tube 18 would result either in fracturing the tube or the resistance rods.

The tube 18 is filled with an insulating compound 35. The resistance opposing current fiow through the resistance unit 7, at ordinary temperatures of said resistance unit and at ordinary voltages, will be the.

resistance of rod 22, as under these conditions the insulating compound and the tube 18 oppose resistance to the flow of ourv rent of a greater order of magnitude than the resistance of rod 22. It is, however, a well known fact, that the dielectric resistance of all insulating materials decreases at high temperatures. Whenever the severity of the discharge establishing an are between electrodesS and a is such that it tends to fuse rods 22, the high temperature thus developed will materially decrease the resistance of the filling 35 and the tube 18, and the enor- 3 mous voltage between opposite ends of the resistance unit, will result in a considerable flow of current. through both resistance 35 and resistance 18, which formerly were iii-- Sula-tors of entirely negligible current-carry- M ingcapacity. As soon, however,as the voltage-drops to normal line voltage, the supply of heat will be entirely inadequate to maintain either tube 18 or tiller 35 at a. high enough temperature to render them apsurge or potential wave and at thesame time the resistance thereof is relatively high, so that upon relieving the surge, the flow of dynamic current tending to follow the same will be immediately checked. The horn electrodes are valuable in dissipating and directing the path of the arc, increasing the length and consequently the resistance of the are as it tends to rise along the horns.

It will now be apparent from the above description that I have provided a very eflicient resistance unit foruse in connection with lightning arresters and the like. The protection rendered by employing. a resistance unit of this type has been found far more effective than heretofore possible, and due to immediate checking of the flow of dynamic current tending to follow a surge upon relieving the same the elimination of shut-downs and destruction of apparatus an increase in efiiciency of the entire system is obtained.

I claim:

1. A resistance element comprising, in combination, a plurality of rods placed end to end, and sleeves of higher conductivity than said rods holding the abutting ends of said rods in alignment and forming an electrical connection between them.

2. In combination a tubular member of insulation. a terminal cap on the upper end of said tubular member, a terminal cap on the lower end of said tubular member, a high resistance conductor connecting said terminal caps, said high resistance conductor comprising a series of high resistance rods of largecapacity having their adjacent ends connected by metallic coupling members.

3. A resistance element for carrying the currents produced by instantaneous discharges. comprising. in combination, a primary resistance element operating as a conductor of high resistance at ordinary temperatures and voltages, a sheath of material in. close contact with said primary element, said sheath being practically non-conducting at ordinary temperatures and voltages. and a casing in close contact with said sheath,

said casing being of different material from 1 said sheath and also non-conducting at ordinary temperatures and voltages.

4. In combination a tubular member of in sulation, a terminal cap on the upper end of said tubular member, a terminal cap on the lower end of said tubular member, resistance means of large capacity in said tubular member of insulation, socket members having axial studs bearing in said upper and lower terminal caps respectively, said socket members encircling the upper and lower ends respectively of said resistance means and yielding means between the ends of said resistance means and said socket members.

5. In combination a tubular member of insulation, a terminal cap on the upper end of said tubular member, a terminal cap on the lower end of said tubular member, resistance means in said tubular member, said resistance means comprising a series of rods of high resistance and large capacity, socket members connecting the opposite ends of said resistance means to said terminal caps and yielding means between one end of said resistance means and one of said socket members.

6. A resistance element comprisin in combination, a plurality of resistance rods placed end to end, resilient means pressing the ends of said rods into contact, and metallic conductors paralleling the path of current across the abutting ends of said rods.

7. In combination, a. casing comprising a tubular sleeve of insulating material, ter minal members at the opposite ends of said sleeve of insulation, a continuous conductor of high ohmic resistance and large discharge capacity connecting said terminal members and an insulating compound forming a second path between said terminal. members.

8. Al resistance element comprising, in combination, a rod, a metallic socket receiving said rod, and resilient means in the bottom of said socket pressing said rod away therefrom.

9. A resistance element comprising, in combination, three telescoped elements forming at ordinary temperatures and voltages a central conductor of high resistance and two insulating sheaths and at the extreme temperatures and voltages incident to a sudden discharge, forming three conductors of difierent conductivity.

10. A resistance element comprising, in combination, a resistor, and fixed terminal members having mechanically telescopic and electrically continuous engagement with the ends of said resistor to allow for thermal expansion thereof, said resistor comprising a plurality of resistance rods with abutting ends, and means for maintaining said resistor at all times under axial compression.

11. In combination. a tubular member of insulation. caps of conducting material closing ofi' opposite ends of said tubular member. and resistance means comprising a series of rods of high resistance and large capacity connected in axial alignment. between said conducting caps.

12. In combination, a tubular member of insulation, conducting members at opposite ends of said tubular member. resistance means arranged in said tubular member and connected between said conducting members, and filler means interposed between the tubular member and said resistance means within the length of the resistance means and maintaining proper disposition of said means in the tubular member.

13. In combination, a tubular member of insulation, conducting members at opposite ends of said tubular member, resistance means comprising a series of rods of high resistance and large capacity connected in axial alignment between said conducting members, coupling members connecting adjacent ends of said resistance rods, and filler means interposed between the tubular mem her and said resistance means within the length of the resistance means and maintaining proper disposition of said means in the tubular member.

14-. In combination, a tubular member of insulation, conducting members at opposite ends of said tubular member, resistance means comprising a series of rods of high resistance and large capacity connected in axial alignment between said conducting members, coupling members connecting adjacent ends of said resistance rods, filler means interposed between the tubular member and said resistance means within the length of said resistance means and maintaining proper lateral disposition of said resistance rods in the tubular member, and resilient means at one end of said resistance means for maintaining proper longitudinal disposition of said rods.

15. A resistance element comprising, in combination. a plurality of resistance rods arranged. end to end, coupling members connecting adjacent ends of said resistance rods, and resilient means acting on one end of said resistance element to maintain proper longitudinal disposition of said rods.

16. In combination, a tubular member of insulation. a terminal cap on one end of said tubular member, resistance means of large capacity disposed in said tubular member and having a socket member on one end. and a recess in the terminal cap for positioning said socket member.

17. In combination, a tube of insulation, a terminal cap member on one end of said tube. resistance means of large capacity disposed in said tube and having a socket memher on one end, a bearing stud on one of said two members. and a recess in the other of said members for receiving said stud, and positioning the socket member.

In witness whereof I hereunto subscribe my name this 3rd day of Nov., A. D. 1919.

ERNEST H. JACOBS. 

